Ureidoalkane diphosphonic acids which are unsubstituted at nitrogen are disclosed in German Pat. No. 2,254,095. These phosphonic acids are readily soluble in water, have good complexing capabilities and are also effective in water treatment.
Ureidoalkane diphosphonic acids are obtained by reacting acyl urea with a mixture of phosphoric acid and phosphorus trichloride at temperatures up to 120 degrees C., preferably in the presence of a neutral solvent, or by heating aminoaklane diphosphonic acids with urea in a stream of dry air or nitrogen according to German Auslegsschrift No. 2,446,749. However, both of these processes are disadvantageous for production of such compounds on an industrial scale, and large quantities of these ureidoalkane diphosphonic acids are difficult to produce.
Despite the efforts of the prior art, there remains a need for better processes of inhibiting the formation of mineral deposits from a water. There is a continuing need for a process which makes use of treatment agents which are more effective than prior art agents and which nevertheless are readily soluble in water and can be produced in a simple and inexpensive manner.